Cpaharley had this mod installed on his 21' when we looked at it prior to ordering ours. He had an additional outlet installed on the corner and installed a 1000 watt Broan heater in the blank panel next to the bath. See Planned modifications to BlackJack….. Mine came with a door there, so I installed it on the 45 degree corner. I installed an extra deep old work fiberglass box for the woods timer and remounted the outlet next to the bathroom door. I was concerned about the heater being too close to the floor, but after lengthy running the floor was barely warm. The Intermatic timer has 1/2/4/8/hold setting. Beats the cube heater sitting on the floor.